Reconstructions for Continuous-Wave Diffuse Optical Tomography by a Globally Convergent Method

In this paper, a novel reconstruction method is presented for Near Infrared (NIR) 2-D imaging to recover optical absorption coefficients from laboratory phantom data. The main body of this work validates a new generation of highly efficient reconstruction algorithms called “Globally Convergent Method” (GCM) based upon actual measurements taken from brain-shape phantoms. It has been demonstrated in earlier studies using computer-simulated data that this type of reconstructions is stable for imaging complex distributions of optical absorption. The results in this paper demonstrate the excellent capability of GCM in working with experimental data measured from optical phantoms mimicking a rat brain with stroke.

Models and Algorithms for Diffuse Optical Tomographic System

Diffuse optical tomography (DOT) using near-infrared (NIR) light is a promising tool for noninvasive imaging of deep tissue. The approach is capable of reconstructing the quantitative optical parameters (absorption coefficient and scattering coefficient) of a soft tissue. The motivation for reconstructing the optical property variation is that it and, in particular, the absorption coefficient variation, can be used to diagnose different metabolic and disease states of tissue. In DOT, like any other medical imaging modality, the aim is to produce a reconstruction with good spatial resolution and in contrast with noisy measurements. The parameter recovery known as inverse problem in highly scattering biological tissues is a nonlinear and ill-posed problem and is generally solved through iterative methods. The algorithm uses a forward model to arrive at a prediction flux density at the tissue boundary. The forward model uses light transport models such as stochastic Monte Carlo simulation or deterministic methods such as radioactive transfer equation (RTE) or a simplified version of RTE namely the diffusion equation (DE). The finite element method (FEM) is used for discretizing the diffusion equation. The frequently used algorithm for solving the inverse problem is Newton-based Model based Iterative Image Reconstruction (N-MoBIIR). Many Variants of Gauss-Newton approaches are proposed for DOT reconstruction. The focuses of such developments are 1) to reduce the computational complexity;2) to improve spatial recovery;and 3) to improve contrast recovery. These algorithms are 1) Hessian based MoBIIR;2) Broyden-based MoBIIR;3) adjoint Broyden-based MoBIIR;and 4) pseudo-dynamic approaches.

Safety and efficacy of frequency-domain optical coherence tomography in evaluating and treating intermediate coronary lesions

AIM To establish whether frequency-domain optical coherence tomography(FD-OCT) is safe and effective in the evaluation and treatment of angiographicallyintermediate coronary lesions(ICL) METHODS Sixty-four patients with 2-dimensional quantitativecoronary angiography(2D-QCA) demonstrating ICL were included. OCT imaging was performed. According to predetermined OCT criteria, patients were assigned to either of 2 groups: OCT-guided percutaneous coronary intervention(PCI) or OCT-guided optimal medical therapy(OMT). The primary efficacy endpoint was to demonstrate the superiority and higher accuracy of FD-OCT compared to 2D-QCA in evaluating stenosis severity in patients with ICL. The primary safety endpoint was the incidence of 30-d major adverse cardiac events(MACE). Secondary endpoints included MACE at 12 mo and other clinical events.RESULTS Analysis of the primary efficacy endpoint demonstrates that 2D-QCA overestimates the stenosis severity of ICL in both the OCT-guided PCI and OMT groups, proving FD-OCT to be superior to and more precise than 2D-QCA in treating this subset of lesions. The primary safety endpoint was fully met with the incidence of 30-d MACE being nil in both the OCT-guided PCI and OCTguided OMT groups. Incidences of secondary endpoints were found to be low in both arms, the only exception being the relatively high incidence of recurrent episodes of angina which was, however, very similar in the 2 groups.CONCLUSION FD-OCT is safe and effective in the evaluation and treatment of ICL. Larger studies are needed to firmly establish the efficacy and safety of FD-OCT in treating ICL across all coronary artery disease population subgroups.

Evaluation of systemic risk factors in different optical coherence tomographic patterns of diabetic macular edema

AIM： To elucidate the relationship between systemic risk factors and different patterns of diabetic macular edema（DME） determined with optical coherence tomography（OCT）. METHODS： In this cross-sectional study, DME was classified by OCT as diffuse retinal thickness（DRT）, cystoid macular edema（CME） and serous retinal detachment（SRD） and the relationship between the systemic risk factors and DME patterns was evaluated. RESULTS： Of the 57 patients with DME, 21（36.8%） had DRT, 24（42.1%） had CME and 12（21.0%） had SRD. Microor macro-albuminuria was significantly higher in the DRT pattern（61.9%） compared with the SRD（50.0%） and CME patterns（25.0%; P=0.040）. Hemoglobin A1 c（Hb A1 c） level was significantly higher and patients were younger in the DRT pattern group（P=0.034, P=0.032）. Best corrected visual acuity was the worst and central macular thickness was the thickest in the CME pattern group. CONCLUSION： Micro-or macro-albuminuria may be more frequent and Hb A1 c level may be higher in patients with DRT. These patients are also seen to be younger than patients with non-DRT.

Transformational change in the field of diffuse optics:From going bananas to going nuts

The concept of region of sensitivity is central to the field of diffuse optics and is closely related to the Jacobian matrix used to solve the inverse problem in imaging.It is well known that,in diffuse reflectance,the region of sensitivity associated with a given source-detector pair is shaped as a banana,and features maximal sensitivity to the portions of the sample that are closest to the source and the detector.We have recently introduced a dual-slope(DS)method based on a special arrangement of two sources and two detectors,which results in deeper and more localized regions of sensitivity,resembling the shapes of different kinds of nuts.Here,we report the regions of sensitivity associated with a variety of source-detector arrangements for DS measurements of intensity and phase with frequency-domain spectroscopy(modulation frequency:140 MHz)in a medium with absorption and reduced scattering coefficients of 0.1 and 12 cm^(-1),respectively.The main result is that the depth of maximum sensitivity,considering only cases that use source-detector separations of 25 and 35 mm,progressively increases as we consider single-distance intensity(2.0mm),DS intensity(4.6mm),single-distance phase(7.5mm),and DS phase(10.9 mm).These results indicate the importance of DS measurements,and even more so of phase measurements,when it is desirable to selectively probe deeper portions of a sample with diffuse optics.This is certainly the case in non-invasive optical studies of brain,muscle,and breast tissue,which are located underneath the superficial tissue at variable depths.

Optical neuroimaging:advancing transcranial magnetic stimulation treatments of psychiatric disorders

Transcranial magnetic stimulation(TMS)has been established as an important and effective treatment for various psychiatric disorders.However,its effectiveness has likely been limited due to the dearth of neuronavigational tools for targeting purposes,unclear ideal stimulation parameters,and a lack of knowledge regarding the physiological response of the brain to TMS in each psychiatric condition.Modern optical imaging modalities,such as functional near-infrared spectroscopy and diffuse optical tomography,are promising tools for the study of TMS optimization and functional targeting in psychiatric disorders.They possess a unique combination of high spatial and temporal resolutions,portability,real-time capability,and relatively low costs.In this mini-review,we discuss the advent of optical imaging techniques and their innovative use in several psychiatric conditions including depression,panic disorder,phobias,and eating disorders.With further investment and research in the development of these optical imaging approaches,their potential will be paramount for the advancement of TMS treatment protocols in psychiatry.

Cyclic Correlation of Diffuse Reflected Signal with Glucose Concentration and Scatterer Size

The utility of optical coherence tomography signal amplitudemeasurement to monitorglucose concentration in tissue phantom and blood samples from human subjectshas been explored. The diffusion equation based calculations as well as invivo OCT signal measurements confirm a cyclic correlation of signal intensity with glucose concentration and scatterer size.

LOCAL CONVERGENCE OF AN EM-LIKE IMAGE RECONSTRUCTION METHOD FOR DIFFUSE OPTICAL TOMOGRAPHY

In this paper, an EM-like image reconstruction iterative formula specifically developed for stable external sources is rewritten as a map towards a fixed point iteration. Eocal con- vergence of the image reconstruction method is then proved. Finally a three-dimensional numerical image reconstruction example is presented.

Spatial sensitivity to absorption changes for various near-infrared spectroscopy methods:A compendium review

This compendium review focuses on the spatial distribution of sensitivity to localized absorption changes in optically diffuse media,particularly for measurements relevant to near-infrared spectroscopy.The three temporal domains,continuous wave,frequency domain,and time domain,each obtain different optical data types whose changes may be related to effective homogeneous changes in the absorption coefficient.Sensitivity is the relationship between a localized perturbation and the recovered effective homogeneous absorption change.Therefore,spatial sensitivity maps representing the perturbation location can be generated for the numerous optical data types in the three temporal domains.The review first presents a history of the past 30 years of work investigating this sensitivity in optically diffuse media.These works are experimental and theoretical,presenting one-,two-,and three-dimensional sensitivity maps for different Near-Infrared Spectroscopy methods,domains,and data types.Following this history,we present a compendium of sensitivity maps organized by temporal domain and then data type.This compendium provides a valuable tool to compare the spatial sensitivity of various measurement methods and parameters in one document.Methods for one to generate these maps are provided in Appendix A,including the code.This historical review and comprehensive sensitivity map compendium provides a single source researchers may use to visualize,investigate,compare,and generate sensitivity to localized absorption change maps.

用于脑功能研究的生物光子学技术研究进展

脑成像技术是生物医学工程学研究的热点。现有传统脑成像手段,如X射线成像(X-ray)、磁共振成像(MRI)等已发展成熟,广泛应用于科学研究和临床诊疗。然而这些成像技术大多具有侵入性、设备体积庞大、成像成本高昂等局限性,且难以适用于特殊人群,如新生儿。该文介绍了几种可用于脑成像的微观光学分子成像模态,这些方法大多无创、成本较低且性能优异,具有广阔的发展前景。在给出了它们的成像原理、系统组成以及关键技术后,总结了已有的研究成果和现阶段研究进展。最后,通过列举和比较这几种成像模态的优缺点讨论了脑成像技术未来的发展方向。

基于观察矩阵的时域扩散光学层析成像方法

荧光极易受到外界因素干扰,影响到光子的输运过程,导致时域扩散光学层析成像效果较差,设计一个基于观察矩阵的时域扩散光学层析成像方法。以光子正常发射的行动轨迹作对照,建立扩散输运模型,使光子在扩散前后能量保持守恒,建立时域稳定条件下重建光子信号方程,计算层析映射率,建立观察矩阵并对观察矩阵中获得的图像小波变换处理,实现基于观察矩阵的时域扩散光学层析成像。实验结果表明,经上述研究的方法成像后,图像的组织体吸收系数、组织体约化散射系数与实际图像曲线基本一致,具有较好的成像效果,满足方法设计需求。

超声光散射成像技术在乳腺肿块中的诊断价值

目的:评价超声光散射成像技术在乳腺肿块诊断中的临床价值。方法:选取2012年10月—2018年6月期间在滨州医学院附属医院进行手术治疗的女性乳腺肿块患者52例(共73个结节)纳入研究,应用超声光散射成像技术对73个乳腺肿块进行检查,评价其超声检查结果与病理诊断的一致性,判断超声光散射成像技术的准确性。结果:术后病理诊断恶性乳腺肿块18个,良性55个。光散射乳腺成像(diffused optical tomography,DOT)诊断恶性乳腺肿块33个、良性40个,超声联合DOT诊断恶性乳腺肿块25个、良性48个。恶性肿块患者的血红蛋白总量高于良性肿块患者,差异有统计学意义(P<0.05)。DOT诊断乳腺肿块的灵敏度、特异度、阳性预测值、阴性预测值、准确率分别为88.89%(16/18)、69.09%(38/55)、48.48%(16/33)、95.00%(38/40)、73.97%(54/73),超声联合DOT诊断效能分别为94.44%(17/18)、87.27%(48/55)、70.83%(17/24)、97.96%(48/49)、89.04%(65/73)。结论:超声光散射成像检查对乳腺肿块性质判断的准确性及敏感性较高,提供了乳腺肿块的代谢信息,为临床诊断提供了新的依据。

抗VEGF治疗对不同类型DME患者黄斑中心凹无血管区的影响

目的基于糖尿病性黄斑水肿(DME)的不同影像类型,采用OCTA探讨DME患者抗血管内皮生长因子(VEGF)治疗前后黄斑中心凹无血管区(FAZ)结构的变化。方法回顾性分析2019年10月至2021年10月来我院就诊的经3+PRN抗VEGF治疗的51例62眼DME患者资料。根据黄斑水肿类型分为弥漫增厚型DME(DRT-DME)组30例(36眼)和黄斑囊样水肿型DME(CME-DME)组21例(26眼)。分别收集两组患者抗VEGF治疗前、治疗后3个月及治疗后6个月的临床资料和OCTA指标,包括最佳矫正视力(BCVA)、黄斑中心凹视网膜厚度(CRT)、FAZ面积、黄斑中心凹旁300μm范围内的视网膜血流密度(FD)和FAZ非圆度指数(AI),并对其进行比较分析。对CME-DME组患者抗VEGF治疗前后OCTA指标差值(治疗前与治疗后6个月差值)之间的相关性采用Spearman相关性分析。结果与治疗前相比,DRT-DME组患者治疗后3个月和治疗后6个月各方位的CRT均下降、BCVA均改善(均为P<0.05),但FAZ面积、FD和AI的差异均无统计学意义(均为P>0.05)。与治疗前相比,CME-DME组患者治疗后3个月和治疗后6个月各方位的CRT均下降、BCVA均改善、FAZ面积均减小、FD均增加和AI均减小(均为P<0.05)。而DRT-DME组和CME-DME组患者治疗后3个月、6个月之间相比,上述各指标间的差异均无统计学意义(均为P>0.05)。对CME-DME组患者抗VEGF治疗前后OCTA指标差值(△=治疗前-治疗后6个月)的Spearman相关性分析结果显示:△FAZ面积与△AI呈正相关(P<0.05);△FD与△FAZ面积、△AI均呈负相关(均为P<0.05);△CRT与△FAZ面积、△AI均呈正相关,与△FD呈负相关(均为P<0.05)。结论抗VEGF治疗对不同影像类型DME患者FAZ结构的影响不同,有助于改善CME-DME患者黄斑区血供,促进FAZ结构的修复,而对DRT-DME患者无明显影响,但随访期内未加重中心凹旁视网膜缺血。

乳腺病灶大小与光散射断层成像血红蛋白浓度的相关性

目的应用超声光散射断层成像分析不同大小的乳腺病灶的总血红蛋白浓度(THC)特征、病灶大小与THC的相关性。方法采用常规超声和超声光散射乳腺断层成像系统,前瞻性研究277例患者共306个乳腺病灶,并与手术病理对照。测量光吸收参数THC,分析病灶大小与THC的相关性,并比较不同大小的组间THC是否有差异。结果306个乳腺病变中,良性147个,恶性159个,良性病灶THC均值(137.36±90.43)μmol/L,恶性病灶THC均值(227.36±88.53)μmol/L,差异有统计学意义(P<0.001)。THC与病灶大小呈正相关,但良性组相关性明显小于恶性组(相关系数0.187vs0.454)。恶性组病灶大小与THC呈线性相关,直线回归方程为Y=143.430+40.785X。结论乳腺病灶大小与THC测值有相关性,恶性病变的THC与病灶大小呈线性相关,而良性病灶THC测值受病灶大小影响较小。

超声弹性成像、光散射成像及两者联合对乳腺肿块良恶性鉴别诊断的价值

目的:探讨超声弹性成像、超声光散射成像及两者联合对乳腺肿块的良恶性鉴别诊断价值。方法:应用弹性成像技术和光散射成像技术对72例患者共82个乳腺肿块进行良恶性的鉴别诊断,并与术后病理结果进行对照。结果:良性48例共58个病灶,恶性24例共24个病灶,超声弹性成像技术、超声光散射成像技术和两者联合对乳腺肿块良恶性鉴别诊断的敏感性、特异性和准确性分别为87.50%、96.55%、93.90%,91.67%、74.14%、79.27%和96.55%、91.67%、95.12%。结论:超声弹性成像在鉴别乳腺良恶性乳腺肿块的准确性较光散射成像高,两者联合较单一检查准确性高。

对比超声定位光散射断层成像与彩色多普勒血流显像检测乳腺癌血供

目的比较超声定位光散射断层成像（DOT）与CDFI检测乳腺癌血供的敏感性。方法 111例乳腺癌患者,经术后病理证实,共118个瘤灶。术前CDFI将乳腺癌血供分为血流丰富、中等及无血流。常规超声检查明确病变后定位行DOT,测量病变血红蛋白总浓度（THC）,以THC 140μmol/L为阈值,比较DOT与CDFI检测不同大小乳腺癌血流的敏感性。结果 118个乳腺癌瘤灶中,57个（48.31%）CDFI表现为血流丰富,36个（30.51%）中等血流,25个（21.19%）无血流;DOT检出99个癌灶（83.90%）的THC〉140μmol/L。对于≤1 cm、〉1~2 cm、〉2~3 cm、〉3 cm的乳腺癌,CD-FI血流显示率分别为28.57%（6/21）、90.20%（46/51）、86.21%（25/29）和94.12%（16/17）,THC增高率分别为76.20%、76.50%、93.10%和100%。结论 DOT可更敏感地检测乳腺癌血管,特别是对于诊断直径≤1 cm的早期乳腺癌,具有潜在临床应用价值。

超声光散射乳腺成像诊断乳腺癌假阳性率分析

目的:超声光散射乳腺成像系统(OPTIMUS)是多模式的可以进行早期乳腺癌普查、诊断及疗效检测的系统。本研究回顾经手术后病理证实的160例乳腺肿瘤的OPTIMUS系统表现与病理结果对比分析,评价OPTIMUS系统的临床应用价值。方法:对160例乳腺肿瘤患者进行OPTIMUS系统检查,将检查结果及手术病理进行总结,并与相应的钼靶及超声结果进行对比,用卡方检验分析结果有无统计学差异。结果:OPTIMUS系统诊断良性病变42例,恶性病变118例。术后病理诊断良性病变60例,恶性病变100例。假阳性率为30.0%,假阴性率为0。OPTIMUS系统诊断乳腺癌准确性88.8%(142/160),敏感性100.0%(100/100);相应超声及钼靶检测准确性分别为87.6%和87.1%,无统计学差异;敏感性分别为86.8%和87.1%,与OPTIMUS系统有统计学差异。结论:OPTIMUs系统对诊断乳腺恶性肿瘤的准确性及敏感性较高,是提高乳腺良恶性病变鉴别诊断的有效方法。

近红外漫射光层析成像实验研究

实验验证了所建立的时间分辨光学层析成像测量系统的光学参量预测能力、多个测量通道的一致性,表明了本测量系统具有层析成像的潜力.研究了采用特征数据量(平均飞行时间、广义脉冲谱技术为基础的用数据类型R)及全时间分辨数据的图像重建算法在光学参量重建准确度、重建出的对象尺寸、空间分辨率等方面的各自优势.

超声光散射成像诊断≤2.00cm乳腺癌

目的探讨超声光散射断层成像（DOT）技术在最大径≤2.00cm乳腺癌中的诊断价值。方法应用超声DOT系统,前瞻性研究95例患者共119个最大径≤2.00cm的乳腺病灶,得到总血红蛋白浓度（TTHC）。以病理诊断为金标准,绘制ROC曲线,计算TTHC的最佳诊断阈值及敏感度、特异度和准确率。结果 119个乳腺病灶中,良性81个,恶性38个。良性组中位TTHC为103.05μmol/L（29.54-273.21μmol/L）,恶性组中位TTHC为182.31μmol/L（80.99-369.61μmol/L）,差异有统计学意义（P〈0.05）。根据ROC曲线分析,TTHC最佳诊断阈值为131.88μmol/L,敏感度86.84%（33/38）,特异度83.95%（68/81）,准确率84.87%（101/119）。结论超声DOT技术是诊断乳腺癌的一种有价值的辅助方法。对于最大径≤2.00cm的乳腺病灶,适当降低TTHC诊断阈值可以提高诊断准确率。

光学相干层析图像的处理研究

提出一种基于各向异性扩散算法Catté腜偷耐枷翊砀慕椒?通过对阈值k的修改以控制扩散强度,可实现在平滑光学相干层析图像的同时保护图像的边缘特征.对不同样品的光学相干层析图像处理.实验结果表明,改进后的算法更有利于噪音的滤除和边缘特征信息的保护.